890 THE VOYAGE OF H.M.S. CHALLENGER. 



Habitat. — October 23, 1874; off Basilar* Strait, Philippine Islands; taken at the 

 surface. 



The carapace is short, being scarcely one-eighth the length of the animal, it is dorsally 

 armed with a small tooth on the cardiac region and another over the frontal crest, and 

 anteriorly produced to a sharply pointed smooth rostrum, on each side of which the 

 frontal region is extended to a long and slender supraorbital tooth, whence the walls 

 descend more abruptly to the lateral margin, the anterior extremity of which is serrate 

 to the fronto-lateral angle, above which and just within the. margin stands a long and 

 slender antennal tooth. 



The pleon is long ; the three anterior somites are subequal in length and dorsally 

 unarmed, the succeeding two are shorter, the fourth being dorsally smooth, but the fifth, 

 while smooth in the median line, is armed with a sharp tooth on each side on the dorsal 

 surface. The sixth somite is longer than the preceding two, it is dorsally smooth and 

 laterally compressed to a greater extent than the others, and is armed on each side at the 

 posterior margin with a long sharp tooth, and ventrally in the median line with a strong 

 tooth. 



The telson is long and slender. 



The ophthalmopoda are thick, clavate, and one-fourth longer than the rostrum ; the 

 ophthalmus is broader than the peduncle, which gradually narrows to the base, which is 

 projected on a short stalk. 



The first pair of antennae has the peduncle very long, longer than the carapace ; the 

 first joint is nearly twice the length of the ophthalmopod, the upper margin is excavate 

 and gives the joint an inferiorly arcuate appearance, the distal extremity is thickened to 

 support the short second and third cylindrical joints, which carry two short flagella, the 

 longest of which is not half the length of the peduncle. 



The second pair of antennae has the flagellum not reaching to the extremity of the 

 first pair, and carries a scaphocerite that is long and narrow, rigid on the outer margin, 

 and distally armed with a tooth that reaches subequally with the first joint of the first pair. 



The oral appendages have not been examined. 



The first pair of gnathopoda is subpediform, and carries a long basecphysis. 



The second pair of gnathopoda is pediform, six-jointed, carries a basecphysis that is 

 nearly as long as itself, and terminates in a short, sharp, unguiculate dactylos. 



The first pair of pereiopoda is a little longer than the second pair of gnathopoda, 

 carries a similar basecphysis, and terminates in a long and slender unguiculate dactylos, 

 each articulation being supported by one or two simple hairs. The second pair of 

 pereiopoda is rather more robust than the preceding, is furnished with a similar 

 basecphysis, and terminates in a sharp unguiculate dactylos ; the inferior angle of the 

 propodos is armed with a long stiff serrate spine. The third pair of pereiopoda is sub- 



